Speaker:  Mikkel F. Andersen,  University of Ontago, New Zealand

Title: Interaction driven dynamics of few atoms in an optical tweezer

Abstract:

An enduring ambition in atomic physics is to build an understanding of interacting macroscopic systems from knowledge of the underlying microscopic dynamics. We use a bottom-up approach to assemble individual few-atom systems in an optical micro-tweezer and study their dynamics. This allows for interrogation of atoms with collisional properties that are unfavourable for many-body experiments as well as direct observation of effects that get hidden by ensemble averaging.

The talk will present results of our recent studies of dynamics of three different atomic interactions. From precisely two atoms we build individual molecules in particular quantum states using photo-association. The experiment reveals that the dynamics of this process is more complex than when photo-associating molecules in a large sample of atoms.

Next, we studied the spin-dynamics of two thermal spin-two atoms undergoing spin-changing collisions in the optical tweezer. We see that it leaves the magnetic sub-levels of the atoms strongly correlated with relative number fluctuations 11.9 dB below quantum shot noise. The observed dynamics may provide a route for thermally robust entanglement generation.

Finally, in an experiment with a cold Rb-85 triad we observe three-body recombination. Our ability to directly observe the number of atoms remaining after individual loss events allows us to discriminate between one- two- and three-body loss events. However, we also observe that the three-body recombination rate is strongly suppressed relative to the expected rate for non-interacting atoms. This could indicate that interactions between the atoms induces correlations that suppress three-body recombination despite Rb-85 having effective attractive interactions with a negative scattering length.

Coffee/tea and bread rolls from 10:00